Selahattin Demirtas, chairman of Turkey's pro-Kurdish Peoples' Democratic Party, says a "safe zone" Turkey and the United States are creating in northern Syria is Ankara's attempt to stop Kurds from forming their own contiguous territory.

Demirtas told the BBC that Turkey's military operations against Islamic State (IS) militants to create the buffer zone along a 110-kilometer stretch of southeastern Turkey's border is a cover to target Kurdistan Workers Party (PKK) rebels.

Washington considers the PKK a terrorist group, but is supporting and equipping other Kurdish forces in Iraq and Syria to fight IS militants.

The White House rejects claims that President Barack Obama agreed to look the other way to secure Turkey's help against IS.

Turkey's President Recep Tayyip Erdogan said on July 28 that it is "not possible to continue" the peace process with Kurdish militants who undermine national unity and integrity.

The PKK says its cease-fire with Ankara effectively ended when Turkey bombed PKK camps in northern Iraq last week.

Turkey began attacks against IS and Kurdish targets on the same day.

Iraq's government on July 29 called the Turkish attacks on the Kurdish militants in northern Iraq "a dangerous escalation and an assault on Iraqi sovereignty."